Pavement cutting and earth excavating device



Sept. 13, 1966 HAYNES 3,272,559

PAVEMENT CUTTING AND EARTH EXCAVATING DEVICE Filed June 21, 1965 9Sheets-Sheet 1 INVENTOR.

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Sept. 13, 1966 HAYNES 3,272,55

PAVEMENT CUTTING AND EARTH EXGAVATING DEVICE Filed June 21, 1965 9Sheets-Sheet 2 a INVENTOR. laws 51, HAY/V515 Sept. 13, 1966 L. E. HAYNES3,272,559

PAVEMENT CUTTING AND EARTH EXCAVATING DEVICE Filed June 21, 1965 9Sheets-Sheet 4 INVENTOR. T l E 104/75 [1 HAY/v55 A TTOP/VEYS Sept. 13,1966 HAYNEs 3,272,559

PAVEMENT CUTTING AND EARTH EXCAVATING DEVICE Filed June 21, 1965 9SheetsSheet 5 I N VEN TOR f [:1 522 Lou/5 1 HAY/V515 Sept. 13;, 1966 H Y3 272559 PAVEMENT CUTTING AND EARTH EXGAVATING DEVICE Filed June 21,1965 9 Sheets-Sheet 6 h: ar/e0 a INVENTOR. laws .A HAY/V515 Sept. 13,1966 L. wmmga 337172559 PAVEMENT CUTTING AND EARTH EXCAVATING DEVICEFiled June 21, 1965 9 Sheets-Sheet 9 Tlca-ZZ PUMP 24E] 24C 24]] 24E 24FINVENTOR. T .L E."-

oufs .6, HA wvas B 9 nrrop/vars United States Patent 3,272,559 PAVEMENTCUTTING AND EARTH EXCAVATING DEVICE Louis E. Haynes, 302 S. 6th St.,Union City, Tenn. Filed June 21, 1965, Ser. No. 465,611 42 Claims. (Cl.299-47) This invention relates to a powered device for removing earthsurfacing material, such asphalt, gravel or the like, or for removinglarge quantities of earth to a depth of up to about eighteen inches on acontinuous basis. More particularly, but not by way of limitation, thepresent invention relates to an excavating or pavement cutting devicewhich utilizes a plurality of sequentially reciprocated blades inconjunction with forward motions supplied by a tractor or otherself-propelled machine for removing earth, asphalt and similar materialsfrom the surface of the earth. This application is a continuationin-partof my United States application 268,133 filed March 26, 1963 now UnitedStates Patent No. 3,219,388.

A great variety of earth working apparatuses of various types have beendeveloped and many of such devices have been directed toward the removalof a substantial quantity of earth from the surface of the ground tovarying depths, with such removal being effected in a continuous manner.Other devices related to the earth removing devices include machineswhich are designed to remove slabs of concrete or asphalt from thesurface of a roadbed for the purpose of renewing the surface, or simplyfor the purpose of reclaiming some of the materials of construction forother uses. Machines of this type have generally been large andcomplicated and, in some instances, have functioned quite well for somespecific utilization, such as removing large quantities of dirt, buthave not been sufficiently versatile to permit their use in a variety ofoperations where surface materials of varying hardness or density andconsistency are encountered.

The present invention comprises a machine which can be utilized for avariety of purposes, and which is characterized by an ability to removelarger quantities of surface materials from the earth than hasheretofore been possible using different types of bladed structures inwhich the blades are fixed and power for scraping or removing thesurface of the earth is developed primarily by a self-propelled vehicleto which the blades are attached. The apparatus of the invention isfurther characterized by great versatility in that the machine may beemployed for removing stumps in the course of clearing new ground,removing without substantial disturbance, a layer of desired thicknessof the earth and then relaying this layer in substantially the sameposition in which it was located prior to removal, removing andconveying from the site of removal substantial quantities of earth whereit is desired to excavate the earth to a certain depth and removing hardsurfaces, such as asphalt or pavement, in instances where it may bedesired to resurface a roadbed or to destroy an old road while salvagingsome of the materials of construction therefrom.

All of the principles which form the basis of the operation of thepresent invention have not been heretofore entirely unknown. Theapparatus of the invention relies primarily upon two forces fordeveloping the cutting, severing and excavating effectiveness of theapparatus, these forces being (a) a rectilinear reciprocating driveimparted to a plurality of blades which are driven in out-of-phase orsequential relation to each other, and (b) the forward motion which isapplied to the machinery as a whole by a self-propelled vehicle, such asa tractor. Blades which move with a rectilinear or reciprocating motionhave heretofore been utilized in small handdriven machines for removingcarpet or linoleum from a floor, but such machines have been entirelyunsuitable for uses of the type to which the present apparatus isadapted, and have not been required to have the mechanical strength ofconstruction, or to deliver the power to the reciprocating blades whichnecessarily characterize the apparatus of the present invention.

Broadly described, the pavement cutting and earth excavating apparatusof the present invention comprises, in combination, a self-propelledvehicle including a prime mover or engine; a power takeoff from theprime mover; a framework spaced from the self-propelled vehicle andcarrying a plurality of blades movably mounted on the framework forreciprocation or rectilinear motion in horizontal planes substantiallyeven with or below the lower surface of the ground engaging portions ofthe selfpropelled vehicle; power transmission means connected betweenthe blades and the power takeoff for driving the blades in sequential,or out-of'phase relation to each other; multiple point hitch connectionelements interconnecting the framework and the self-propelled vehicle;and actuating means on the self-propelled vehicle for actuating themultiple point hitch connecting elements to raise and lower theframework, and to incline the framework and the blades carried therebywith respect to a horizontal plane.

To more specifically describe certain aspects of the invention, theframework which is connected to the selfpropelled vehicle by themultiple point hitch connecting elements includes a pair of verticallyextending, horizontally spaced side walls or plates extending parallelto the direction of movement of the reciprocating blades; a materialsupporting inclined ramp positioned adjacent the blades and extendingupwardly and rearwardly therefrom; and a material moving conveyorpositioned adjacent the ramp for receiving material therefrom andextending transversely between the vertically extending side walls ofthe framework.

Various types of drive systems may be used for driving the blades inreciprocation from the power takeoff of the self-propelled vehicle.Several preferred types of these will be described in the detaileddescription of the invention which follows hereinafter. In eachinstance, however, the blades are reciprocated in a directioncorresponding to the direction of travel of the self-propelled vehicleand framework, and the blades are moved in outof-phase relation to eachother; that is, one of the blades will complete a cutting stroke asanother is commencing its cutting stroke, and as yet another isretracting from its cutting stroke, etc. The cutting forces which comeinto play to remove the surface of the earth or surfacing material, suchas pavement, are thus (a) the forward motion of the self-propelledvehicle and (b) the reciprocating motion of the cutting blades. In apreferred embodiment of the invention, means is provided forsynchronizing these two motions so that the machine can be usedefficiently in varying types of soils, or in removing surfacingmaterials of varying hardness and consistency.

Since less force is required to move materials to the rear of theframework away from the cutting blades if the inclination of theinclined ramp and conveyor is relatively small, a preferred constructionof the invention further contemplates a low profile conveyor arrangementin which the transmission between the power takeofi and the blades is anovel combination of elements compactly constructed for occupying aminimum of space below the conveyor.

In operation, the framework carrying the reciprocating blades is drivenor pulled by a tractor or the like so as to cause the reciprocatingblades to bite into the earth or through the pavement or other surfacematerial, according to the purpose to be accomplished. As the frameworkis pulled along the gro-und, the blades are sequentially reciprocatedinto and out of the earth at a depth determined by an initial setting onthe multiple point hitch connection. The excavated earth or removedsurface material is forced to the rear of the framework and onto theconveyor. Any desired disposition may be made of the dirt moved by theconveyor. It has been found that a considerably greater rate of earthand surfacing material removal can be accomplished with the apparatus ofthe invention than has been attainable with any device known toapplicant which has heretofore been used for this same general purpose.

From the foregoing description of the invention, it Will have 'becomeapparent that it is an important object of the present invention toprovide an earth excavating and pavement cutting, or surface materialremoving, device which can quickly and efficiently remove largequantities of earth or surfacing material, and convey such material to alocation where it may be conveniently disposed of in any manner desired.

A further object of the present invention is to provide a mechanicallyrugged, self-propelled apparatus which can be used to slice away asurface layer of the earth to any depth desired up to about eighteeninches.

An additional object of the present invention is to provide an earthexcavating apparatus which includes a plurality of reciprocating bladesdriven in sequence by novel, mechanically rugged drive systems which canbe operated from a power takeoff on a tractor or similar self-propelledvehicle.

Another object of the invention is to provide a selfpropelled earthexcavating apparatus which can effectively remove a layer of earthwithout an undesirably high degree of disturbance to the earth, and thenpermit the earth to be redeposited in substantially the same locationfrom which it was removed.

Another object of the present invention is to provide a device which caneffectively remove asphalt from a roadbed and convey the cut portions ofthe asphalt to a suitable heated tank where the asphalt can be quicklyremelted and respread, thus saving considerable cost.

A further object of the invention resides in the provision of a devicewhich can be quickly and effectively attached to a conventional landsurface self-propelled vehicle in a manner which permits the device tohe driven into the earth to a desired depth, at which the depth thedevice will automatically level off and proceed to remove the earthalong a horizontal plane therein.

Another object of the invention is to provide means connected to thecutter blades of the device for removing asphalt or other surfacingmaterials so as to reciprocate some of these blades out of phase withother blades to thereby make the device continuously effective forcutting pavement or asphalt.

An additional object of the invention is to provide an earth excavatingand surfacing material removing device which can be driven by aself-propelled vehicle using a power takeoff therefrom, and includingmeans for synchronizing the rate of movement of the self-propelledvehicle and excavating device along the ground with the reciprocatingmovement of the cutting blades which are provided in the device.

Another object of the invention is to provide an earth excavating devicewhich is efficient in operation, and which requires a minimum number ofparts and maintenance.

An additional object of the invention is to provide an earth excavatingand pavement cutting device which is very strongly constructed, ismechanically durable and is characterized by a long and trouble-freeoperating life.

In addition to the foregoing described objects and advantages, otherobjects and advantages will become apparent as the following detaileddescription of the invention is read in conjunction with theaccompanying drawings which illustrate various aspects and embodimentsof the invention.

In the drawings:

FIGURE 1 is a side elevational view of one embodiment of the presentinvention showing a tractor vehicle in use to control the orientation ofexcavation elements relative to the ground and to propel the apparatusin its operation.

FIGURE 2 is a detail view illustrating the elements utilized to connectthe earth excavating and pavement cutting device of the invention to atractor by a four point hitch connection, and showing the manner inwhich the hitch links and the driving elements connected thereto areused to adjust the elevation and vertical inclination of the pavementcutting device with respect to the ground.

FIGURE 3 is a View similar to FIGURE 2 illustrating the earth excavatingand pavement cutting device as it is positioned by the actuatingelements of a tractor preparatory to driving the device into the ground.

FIGURE 4 is a plan view further illustrating the manner in which theearth excavating and pavement cutting device is connected to the tractorby a plurality of hitch links.

FIGURE 5 is a longitudinal sectional view through the center of oneembodiment of the apparatus of the invention, and illustrating therelationship of the various components utilized in the invention, exceptfor the selfpropelled vehicle or tractor which supplies the power foroperation of the apparatus.

FIGURE 6 is a sectional view showing the interior of the gear box whichhouses the gearing used to interconnect a drive shaft with a crankshaftused in the invention.

FIGURE 7 is a sectional view taken substantially along the plane of theline 7-7 of FIGURE 5.

FIGURE 8 is a sectional view taken substantially along the plane of theline 88 of FIGURE 5 and illustrating the guide means used for guidingthe reciprocating cutter blades utilized in the embodiment of theinvention illustrated in FIGURES 1 through 9.

FIGURE 9 is a fragmentary side elevational view of the apparatus of theinvention with the cover housing for the conveyor drive assembly removedto more clearly illustrate the latter.

FIGURES 10 through 16 illustrate a different embodiment of the presentinvention, various aspects and details of which are depicted in theseveral figures as follows:

FIGURE 10 is an elevational view illustrating the manner in which theearth excavating and pavement cutting framework and reciprocating bladesare connected to a self-propelled vehicle, such as a farm tractor, usinga three point hitch connection.

FIGURE 11 is a longitudinal sectional view taken in a vertical planethrough the earth excavating and pavement cutting portion of theapparatus illustrated in FIG- URE 10 and showing the moving parts ofthis portion of the apparatus as such parts would appear if one of thevertically extending side walls or plates of the framework were removed.

FIGURE 12 is a longitudinal sectional view taken in a vertical plane andextending through the earth excavating and pavement cutting portion ofthe invention illustrated in FIGURE 11 with the FIGURE 12 section beingtaken near the centerline of the framework used to support the dirtmoving conveyor and the reciprocating blades.

FIGURE 13 is a plan view of the earth excavating and pavement cuttingportion of the invention as it appears when viewed from the above withthe conveyor belt and lowermost conveyor roller removed in order tobetter illustrated certain elements of the invention.

FIGURE 14- is a horizontal sectional view taken through the earthexcavating and pavement cutting portion of the machine along line 1414in FIGURE 11.

FIGURE 15 is a perspective view of the earth excavating and pavementcutting portion of the assembly shown in FIGURE 10.

FIGURE 16 is a section taken along line 16-16 in FIGURE 13.

FIGURES 17, 18 and 19 illustrate yet another embodiment of the inventionwhich is particularly useful by reason of the low profile conveyor, andlow surfaces over which the excavated dirt is moved, and whichincorporates a novel transmission system which is enclosed in a sealedlubricating chamber, and a particularly sturdy drive system for thereciprocating blades. The several figures in this series may bedescribed as follows:

FIGURE 17 is a perspective view illustrating the modified embodiment ofFIGURES 17 through 19 as it appears when detached from theself-propelled vehicle to which it is adapted to be attached by a threepoint hitch connection.

FIGURE 18 is a side elevational view of the earth excavating andpavement cutting device depicted in FIG- URE 17 as the same would appearwith one of the vertically extending side plates removed. A portion ofthe hollow central partition which houses the vertically extending driveshaft utilized in this embodiment of the invention has been broken awayto better show the position of the drive shaft.

FIGURE 19 is a sectional view taken along the horizontal plane definedby line 1919 in FIGURE 18.

FIGURES 20 and 21 illustrate yet another embodiment of the invention inwhich yet a different drive system is used to convey power from thepower takeoff on a self-propelled vehicle to the reciprocating bladesused in the earth excavating and pavement cutting portion of theinvention. In these figures, FIGURE 20 is a view of the earth excavatingand pavement cutting portion of the apparatus similar to that shown inFIGURE 18, i.e., this portion of the apparatus as it would appear whenviewed in elevation with one of the vertically extending side platesremoved, and a portion of the hollow central partition broken away tobetter illustrate the drive shaft.

FIGURE 21 is a horizontal sectional view taken along the plane definedby line 2ll21l in FIGURE 20. A portion of the gear drive used in thisembodiment of the invention has been broken away in order to betterillustrate the manner in which the several gears carrying eccentricstuds or pins are utilized to drive the reciprocating blades inout'of-phase relation to each other.

FIGURE 22 is a partially schematic view of a modified drive system whichis utilized in a preferred embodiment of the invention for driving thereciprocating cutting blades used in the invention in out-of-phaserelation. This figure depicts the manner in which the hydraulic drivesystem is adapted to permit the rate at which the blades arereciprocated to be synchronized with the rate at which theself-propelled vehicle used to move the earth excavating and pavementcutting device is advanced along the ground.

FIGURE 23 is a sectional view taken along line 23--23 of FIGURE 22.

FIGURES 24a-24f are schematic sectional views taken through several ofthe fluid injection and discharge ports used in the hydraulic drivesystem depicted in FIGURES 22 and 23, and showing the manner in whichthese ports are circumferentially spaced around a solid cylinderthroughwhich they extend.

Referring now to the drawings in detail, and particularly, to FIGURES 1through 4, the main framework used in the earth excavating and pavementcutting device of the invention is designated gene-rally by referencecharacter It). The framework includes a pair of horizontally spaced,vertically extending side Walls 12 and 14 which are connected to eachother by a transversely extending plate 16 which is secured to thevertically extending plates 12 and 14 at the lower edges thereof. Thevertically extending side walls 12 and 14 each have secured adjacent therear edge 18 thereof, a pair of vertically spaced connecting pins, theuppermost of which are designated by reference character 29, and thelowermost of which are designated by reference character 22. Pivotallyconnected to the pins and 22 are pairs of elongated hitch links 24- and26. The links 24 connected to the uppermost pins 20 are utilized forcanting or inclining the framework 10 with respect to the surface of theearth, as hereinafter explained. The hitch lengths 24 are connected attheir other ends to a hydraulic cylinder 27 or other actuating mechanismdisposed on a suitable self-propelled vehicle, such as a tractordesignated generally by reference character 28 and illustrated inFIGURE 1. The large hitch lengths 26 which are connected at one of theirends to the lowermost pins 22 on the framework 10 are rigidly secured attheir other ends to an arm 30 on the tractor 28, which arm 39 ispivotally connected to a support beam 32 for pivotation about a pivotalaxis 34. The arm 30 is driven in its pivot-a1 movement by a suitablehydraulic cylinder 36 mounted on the tractor and fixed to an uprightstanchion 38.

Power for the operation of the earth excavating and pavement cuttingapparatus of the invention is developed by the engine an of the tractor28, and is transmitted to the reciprocating blades mounted on theframework 10 (as hereinafter described) by a suitable power takeoff 42from the engine '40. The power takeoff 42 is connected to a couplingshaft 43 which is connected through a universal joint 4-4 to a driveshaft 46 which enters a gear box 43 mounted on the horizontallyextending transverse plate 16. A bevel ring and pinion type gear 49 ismounted in the gear box 48 as illustrated in FIG- URE 6. The bevel ringand pinion gear 49 is used to drive a crankshaft designated generally byreference character 50 from the drive shaft 46.

The crankshaft 50 extends transversely across the framework 10 and isjournaled at its ends in a pair of bearings 52 and 54 mounted on thevertically extending side plates 12 and 14 (see FIGURE 7). Thecrankshaft 50 is provided with a plurality of radially offset,circumferentially spaced throw portions 56 which are spaced from eachother along the longitudinal axis of the crankshaft. The number ofthrows 56 which are provided correspond in number to the number ofreciprocating blades which will be utilized in the invention ashereinafter explained. The circumferential spacing of the throws ispreferably equal and corresponds to 360 divided by the number of throwswhich are provided (four in the illustrated embodiment).

Connecting rods or crank arms 58 are pivotally jouirnaled at one oftheir ends 60 on each of the throws 56. At their opposite ends 62, thecrank arms 58 are pivotally connected by means of crank pins 63 (seeFIGURE 5) to knuckle bearings 64 which are rigidly secured inhorizontally spaced relation to the rear portions of each of a series ofelongated cutter blades designated generally by reference character 66.The construction of the cutter blades may perhaps best be understood byreferring to FIGURES S and 7. Each of the cutter blades 66 includes anenlarged head 68 which is tapered to a sharp cutting edge '70 at theforward end thereof. The cutter blades 66 further include a transverselyreduced shank portion 72 which is connected to, or formed integrallywith, the enlarged head 68, and which supports at its rearmost end thebearing knuckles 64. It will also be noted in referring to FIGURE 5 thatthe enlarged head 68 of each of the cutter blades is thicker in itsvertical dimension than the reduced shank portion 72 of the blade.

In order to support the cutter blades 66 in their reciprocatingmovement, hereinafter described, a cutter blade supporting bar 74extends transversely across the framework 10 and is secured to the loweredges of the vertically extending side plates 12 and 14. Spaced abovethe cutter blade supporting bar 74 by a distance sufficient to permitthe reduced portions 72 of the cutter blades to be extended therethroughis a cutter blade retaining bar 76. The cutter blade retaining bar 76 isprovided with a relatively flat lower surface and an arcuate orconcavely dished upper surface so as to permit the reduced shankportions 72 of the cutter blades 66 to slide against the lower surfaceof the cutter blade retaining bar and to permit a conveyor to be mountedin juxtaposition to the forward, upper surface of the cutter bladeretaining bar for a purpose hereinafter explained.

In order to guide and to maintain the position of the cutter blades 66in the course of their reciprocating motion, a plurality of spacer guideplates 80 are provided between the cutter blade supporting bar '74, andthe cutter blade retaining bar 76 at spaced intervals along thetransverse extent of these members, with the spacing between the spacerguide plates corresponding to the width of the reduced shank portions 72of the cutter blades 66. It will thus be seen in referring to FIGURE 8that the spacer guide plates 86, the cutter blade supporting bar 74 andthe cutter blade retaining bar 76 provide channels in which the cutterblades may move during reciprocation, which channels function tomaintain the alignment of the cutter blades and guide them in theirmove-ment.

For the purpose of preventing an accumulation of dirt around the cutterblades 66, and to permit excavated dirt to be moved to a position forpermitting more convenient disposal, the apparatus of the invention isprovided with an endless conveyor belt 84 which is extended over aforward roller 86 positioned in the concavely dished upper surface ofthe cutter blade retaining bar 76, and a rear roller 88 spacedvertically above the crankshaft '50. The drive for the conveyor 84 isobtained by mounting a sprocket or pulley 90 on the end of a shaft 92which carries the roller 88. The pulley 96 is positioned above asprocket or pulley 94 carried on one end of the crankshaft 50 whichprojects through the side wall 12, as best illustrated in FIGURES 7 and9. An endless belt 96 drivingly interconnects the pulleys 90 and 94- sothat the rotary motion of the crankshaft 50 is transmitted to the shaft92 to which the conveyor roller 88 is keyed. A suitable cover or housing98 is secured to the vertically extending side wall 12 and covers thepulleys 90 and 94 and the belt 96, as best illustrated in FIGURES 3 and9.

An arcuate slide plate 100 is secured between the vertically extendingside walls 12 and 14 of the framework 10 and is positioned to the rearof the conveyor belt 84 to receive dirt therefrom and convey the dirt tothe rear of the framework. Any suitable means of disposal may beprovided on the framework in addition to the conveyor 84 and slide plate100, such as a heated hopper for receiving materials such as asphalt orpavement for melting these materials for reutilization. There may alsobe an additional conveyor system (not shown) connected to the rear ofthe framework 10 for removing dirt excavated by the apparatus to aremote location, or for loading the dirt into a hopper, dump truck orsimilar device.

In the operation of the embodiment of the invention illustrated inFIGURE 1, the framework 10 can initially be elevated and inclined withrespect to the surface of the earth by means of the hitch links 24 and26 as illustrated in FIGURES 2 and 3. The heavy, more mechanicallysturdy links 26 are employed for bodily lifting the framework 10 out ofthe earth, or above the surface of the earth, and the links 24 areutilized to cant or incline the framework with respect to the surface ofthe earth. After positioning the apparatus, as illustrated in FIGURE 3,the tractor 2%; or other driving, self-propelled vehicle is movedforwardly in the direction of the framework 10 and, at the same time,power is transmitted to the cutter blades 66 via the power takeoff 42and shafts 43 and 46. As the tractor 28 moves forward, the framework 10is forced into the earth and is then leveled out by the use of the hitchlinks 24, accompanied by a gradual lowering of the hitch links 26. Thepower input to the gear box 48 drives the crankshaft 50 through the ringand pinion gearing 49 located in the gear box. As the crankshaft 54 isrotated, the horizontally spaced eccentric throws 56 located thereon arealso rotated and cause the connecting rods 58 to move with anoscillating movement which is translated to rectilinear or reciprocatingmotion by reason of the pivotal connection between the connecting rodsand the throws 56 at one of their ends, and the bearing knuckles 64 viathe crank pins 63 at their other ends.

It will be noted in referring to FIGURE 5 that the forward or powerstroke delivered to the cutter blades 66 through the connecting rod 58occurs at the time when the connecting rods are most nearly aligned withthe path of motion of the cutter blades. Stated differently, the forwardor cutting stroke of the cutter blades 66 commences as the eccentricthrows 56 approach the transverse plate 16 in their clockwise rotatingmovement and continues as the throws pass through their point of nearestapproach to the transverse plate 16. This construction considerablyimproves the mechanical strength of the power transmission structure,and increases the operating life of the cutter blade drive mechanism.

As the cutter blades are reciprocated or driven in rectilinear motion,they are guided in this motion by the cutter blade supporting bar 74-,the cutter retaining bar 76 and the spacer guide plates 80. The cutterblades 66 are driven forwardly into the earth by the motion of thecrankshaft 50 and through the connecting rods 58 so that the cutterblades have a compound motion imparted to them by the drive system fromthe power takeoff 42, as well as the forward motion of the tractor 28.The motion of the tractor 23 and the cutter blades can be synchronizedto give maximum digging effectiveness in soils of varying consistenciesand hardness. The level at which the blades 66 cut through the earth canbe adjusted by proper manipulation of the hitch links 24 and 26, and themachine is capable of removing earth at depths up to nearly two feet.

As the earth removed by the cutter blades 66 moves toward the tractor 28by reason of the forward motion of the tractor, it passes over thecutter retaining bar 76 and onto the conveyor belt 84. The conveyor beltmoves the loose earth upwardly and onto the slide plate 100. From theslide plate 100 the dirt may be removed to a remote location fordisposal, or may be permitted to return to the earth as in a plowingoperation, or in an operation where it is merely desirable to loosen ormove the upper surface of the soil. The machine as thus far describedcan also be used for removing a hard surfacing material, such as asphaltor other paving material when it is desired to renew or replace thesurface of a roadbed. The asphalt is sheared away or cut to a desireddepth by the cutter blades 66 and the pieces of asphalt are carriedupwardly by the conveyor belt 84 and deposited on the slide plate 100.From the slide plate 106 the asphalt may be deposited in a melting vat(not shown), further conveyed to a dump truck or disposed of in anyother suitable manner.

Another form or embodiment which the invention may assume is illustratedin FIGURES 10 through 16 of the drawings. In referring to these figures,a tractor vehicle 106 of the agricultural type is positioned ahead of aframework 108 which carries the earth excavating and pavement cuttingapparatus used in the invention. The framework 108 includes, similarlyto the embodiment illustrated in FIGURES 1 through 9, a pair ofvertically extending, horizontally spaced side walls 116 and 112. Ahorizontally extending, forward transverse blade support member 114 isconnected at each of its opposite ends to the side walls 110 and 112, aswell as to the forward end of a pair of horizontal Q blade supportplates 116 secured to the lower edge of each of the side walls and 112.

The side walls 110 and 112 are further interconnected by a transverse,generally L-shaped brace 118 which is spaced upwardly from the lowerends of the side walls 110 and 112 and toward the rear, vertical edges12f) thereof. Another structural element interconnecting the side walls110 and 112 is a large angle iron, gear box-supporting, transverse beam122 which extends between the side walls adjacent the upper edges 123thereof and provides a support for a gear box and drive shaft ashereinafter explained.

A blade shank guideway designated generally by reference character 124-extends transversely between the side walls 112 and 110' and is securedat its opposite ends to the lower edges thereof. The blade shankguideway 124 includes a lower plate 126, an upper plate 128 and a plurality of spacer members (not visible) which function to retain theupper and lower plates 128 and 126, respectively, in spaced relation toeach other, and also to guide the cutter blades in their reciprocationmotion, as will be hereinafter explained. The lower plate 126 of theblade shank guideway 124 extends rearwardly in the framework 112 inhorizontal coplanar alignment with the lower edges of the side walls 112and {111} to a point slightly beyond the rear edges of the side walls.

The lower plate 126 is provided with a plurality of slots or apertures132 in transversely spaced relation therealong to permit dirt movedrearwardly by the cutter blades and infiltrating under the conveyor(hereinafter described) to gravitate from the machine during theoperation thereof. The upper plate 128 of the blade shank guideway 124carries a plurality of rollers which are journaled therein and arepositioned to bear against the upper surface of the shanks of the cutterblades as the same are reciprocated through or between the upper andlower plates 128 and 126, respectively, as hereinafter explained.

Welded or otherwise suitably secured to each of the side walls 110 and112 at positions adjacent the forward edge 134 thereof, and spaced wellup on the respective side walls are a pair of outer hitch brackets 136and 138, respectively. The outer hitch brackets 136 and 138 are providedwith a plurality of channels having apertures in the sides thereof topermit the outer hitch links which are secured therein to betransversely adjusted in their points of attachment as may be desired.In referring to FIGURE 10, it will be noted that the framework 112 isconnected to the tractor 1116 by a three point hitch connection whichincludes outer hitch links 140 which extend from the brackets 136 and138 to the tractor 106, and which are connected to suitable actuatingmeans on the tractor to permit the framework 108 to be raised or loweredin a vertical direction, as hereinafter more fully explained.

A third bracket for connecting the third and central hitch link whichextends between the tractor 1116 and the frame 103 is provided by a pairof braces 142 which are welded or otherwise suitably secured at one oftheir ends 144 to the outer hitch brackets 136 and 1 38, and which arebent inwardly over a major portion of their length and then upwardly attheir upper ends 146 to provide parallel opposed ears forming a hitchbracket to receive one end of the central hitch link 1148. The upperends 146 of the members 142 are apertured as designated by referencecharacter 150 (see FIGURE 11) to permit a pin to be passed through theend of the central hitch link 148 and the upper ends 146 of the members142. The hitch link 148 is connected at its forward end to an actuatingmechanism (not visible), such as a hydraulic piston and cylinderassembly, on the tractor 106 to permit the framework 108 to be pivotedabout a horizontal axis extending through the points of connection ofthe outer hitch links 140 to their respective hitch brackets 136 and133. In order to add structural strength and support to the members 142,a pair of angle braces 154 are extended 19 between the transverse angleiron beam 122 and the members 142, as best illustrated in FIGURE 13.

The cutter blades employed in the embodiment of the inventionillustrated in FIGURES 10 through 16 are somewhat similar to the cutterblades illustrated in the embodiment of the invention depicted inFIGURES 1 through 9 and previously described. The cutter blades aredesignated generally by reference character and include a sharpenedcutting edge portion 162 and a shank portion 164 extending rearwardlyfrom the cutting edge. The shank portion 164 of each cutter blade 160 isslidingly supported on the transverse blade support member 114 and thelower plate 126 of the shank guideway 124. It will also be noted inreferring to FIGURE 12 that the shank portions 164 of the cutter blades16 pass beneath the upper plate 128 of the shank guideway 124 and are incontact with the rollers 132 carried thereby.

In order to guide and further support the shank portions 164 of theblades 160 during the reciprocating motion of the blades, a plurality ofdouble channel guide bars 165 are extended between the shank guideway 124 and the transverse blade support member 114, as illustrated inFIGURES 13 and 16. The channel guide bars 165 are horizontally spacedfrom each other and are positioned to slidingly engage the side edges ofthe shank portions \164 of the blades 160. The I-shaped crosssectionalappearance of the guide bars 165 is illustrated in FIGURE l6. In theillustrated embodiment, the guide :bars 165 include a lower plate 166, atop plate 167 and a spacer bar 168 between the lower and top plates.

In order to protect the laterally outer edges of the shank portions 164of the two outermost blades 160 from becoming impacted with dirt duringoperation of the apparatus, a pair of horizontally extending protectivecover plates 169 are secured along each of the side walls 110 and 112just above the blades. Confining guideways or channels are thus formedfor these particular blade shank portions by the horizontal supportplates 1 16 and the cover plates 169 attached in pairs to each of theside Walls 110 and \112.

In order to better facilitate movement of the frame 108 along the groundduring an earth excavating or pavement cutting operation, a shaft 170 ispositioned at the lower rear end of the framework 108 and is journalledin horizontally spaced brackets 17'1 welded or otherwise secured to thelower plate 126- and the side walls 110 and 112. A roller 158 is keyedto the shaft 170' and projects slightly below the lower plate 126 toreduce the frictional drag of the framework 108 as it is pulled behindthe tractor 106.

The transmission system utilized to drive the cutter blades 160 inreciprocating, out-of-phase motion includes a includes a power inputshaft 172 which is adapted for connection through a universal joint 173to a power takeoff shaft 174 extending from the tractor 106. The powerinput shaft 172 extends through a journal block 175 supported from theupper ends 146 of the members 142 and into a gear box 176 mountedcentrally on the transverse angle iron beam 122. A ring and pinion orother suitable gear (not seen) enclosed in the gear box 176 transmitsthe rotational movement of the power input shaft 172 to a transversedrive shaft 177. The transverse drive shaft 177 extends through ajournal block mounted on the transverse angle iron beam 122 near the endthereof and is keyed at its outer end to a drivesprocket 178. A portionof the transverse angle iron beam 122 is cut away to permit a drivechain 179 to be extended around the drive sprocket 178 and downwardlyalong the side wall 110.

At its lower end the drive chain 179 is passed around a driven sprocket18% which is mounted on one end of the crankshaft 181. The crankshaft181 is shaped similarly to the crankshaft 50, as illustrated in theFIGURE 1 through 10 embodiment, and which has been described inreferring thereto. Thus, the crankshaft 181 is provided with a pluralityof radially offset, circumferentially staggered throws 182 spaced fromeach other over its length and corresponding in number to the number ofcutter blades used in the apparatus. Similarly also, the throws 182 arearranged circumferentially around the crankshaft 181 to provideout-of-phase actuation of the blades 160. The crankshaft is extendedthrough a plurality of journal-carrying, trapezoidally-shaped verticalblocks 183, and is rotatably supported in journals carried thereby. Thevertical blocks 183 are secured at their lower ends or bases to thelower plate 126, and at their upper ends to the L-shaped brace 118.

Each of the throws 182 on the crankshaft 181 is connected by means of acrank pin 184 to one end of a connecting rod 185 which is secured by apin 186 extending through its other end to a connecting bracket 187secured to, and extending upwardly from, the shank portion 164 of one ofthe cutter blades 160. Thus, each of the cutter blades 160 is connectedby a connecting rod 185 to one of the throws 182 of the crankshaft 181.

The conveyor system used in the embodiment illustrated in FIGURESthrough 16 is best illustrated in FIGURES ll, 12 and of the drawings.The conveyor system includes an endless belt conveyor 188 which isextended around a pair of rollers 189 and 190 mounted in the positionsillustrated in FIGURE 11. The roller 189 is supported on a shaft 191which is carried by a plurality of vertical shaft supporting members 192secured at their lower ends to the lower plate 126 and projectingupwardly and rearwardly therefrom so as to position the roller 189slightly to the rear of the framework 108. At its end which is mostproximally positioned with respect to the side wall 112, the shaft 191is provided with a drive sprocket 193 which permits the shaft to bedriven in rotation by a chain 194- extended around the sprocket 193 atone end thereof, and around a second sprocket 195 which is connected tothe opposite end of the crankshaft 181 from the end thereof whichcarries the driven sprocket 180.

The roller 190 is keyed to a shaft 196 which is rotatably journaled inthe side walls 110 and 112 of the framework 108.

In order to protect the transmission mechanism and the moving bladeshanks 164 from impaction by dirt which may slip off the conveyor belt188 and gravitate downwardly within the framework 108, a pair ofoverhanging protective plates 197 are secured to the side walls 110 and112 and extend outwardly over the opposed edges of the endless conveyorbelt 188, and preferably bear lightly thereagainst to form a seal toprevent by-pass of dirt. It will be noted in referring to FIGURE 11 thatthe cover plate 197 which is secured to the side wall 110 is eitherslotted or is interrupted and broken away over a portion of its lengthin order to permit the chain 179 interconnecting the drive sprocket 178with the driven sprocket 180 to be passed through the cover plate.

A final element which is incorporated in the embodiment of the earthexcavating and pavement cutting apparatus illustrated in FIGURES 10through 16 is a lift plate 198 which is utilized to receive dirtloosened and removed by the cutter blades 160, and to move this dirtupwardly onto the endless conveyor belt 188. The lift plate isillustrated in section in FIGURES 11 and 12, and in elevation in FIGURESl3 and 15 and is designated by reference character 198. It will be notedin referring to the sectional views of the lift plate 198 that the plateis inclined with respect to the vertical at approximately the same angleas the angle of inclination of the endless conveyor belt 188, and thatthe lift plate 198 is aligned with the conveyor belt so that dirt canmove smoothly from the lift plate onto the conveyor belt. The lift plate198 extends transversely across the framework 108 and is secured at itsopposite ends by bolting to anchor 12 plates 199 welded or otherwisesuitably attached to each of the vertically extending side walls and112.

In the operation of the embodiment of the invention illustrated inFIGURES 10 through 16, the framework 108 is attached behind the tractor106 by a three point hitch connection utilizing the outer hitch linksand the central hitch link 148. The outer hitch links 140 can be liftedupwardly to vertically elevate or lower the framework 108 when it isdesired to pull the framework out of the ground or lower it into aresting position thereon. The central hitch links 148 can be extended inlength by a conventional actuating mechanism on the tractor 106 to causethe framework 108 to pivot about a horizontal axis extending through thehitch brackets 136 and 138.

By canting or inclining the framework 108 with respect a to the surfaceof the earth, it may be caused to bite downwardly or dig into the earth,and the setting on the central hitch link 148 determines the depth towhich the cutter blades will dig before the framework levels out andassumes a horizontal position. An interesting aspect of the invention isthat the framework will automatically level out at a selected depthwithout further actuation of the central hitch link 1148 as a result ofthe change in the vertical position of the framework 108 with respect tothe tractor 106 as the framework settles down to the desired depth. Thisaction occurs because of the fixed radius of the central hitch link 148once its length is set, and the manner in which the framework is pivotedon the two outer hitch links 140.

Once the cutter blades 160 have reached the desired cutting depth, theexcavating operation commences or, alternatively, in a different use ofthe apparatus, the surfacing material, such as asphalt or other pavingmaterial, commences to be stripped away to a desired depth. The cutterblades are driven in rectilinear or reciprocating motion by powerdelivered from the power takeoff 174 of the tractor 106. Thus, the powerinput shaft 172 is driven in rotation and, through the gearing locatedin the gear box 176, drives the drive shaft 177 in rotation. Through thesprockets 178, chain 179 and drive sprocket 180, the crankshaft iscaused to rotate in the journals provided in the journal-carrying blocks183. Rotation of the crankshaft 181 in turn causes the cutter blades 160to be rotated in out-of-phase relation because of the manner ofconnection of the connecting rods to the throws 182 of the crankshaft,as hereinbefore explained.

As dirt or paving material is cut away by the cutter blades 160, itmoves up over the lift plate 198 and moves onto the endless conveyorbelt 188. The endless conveyor belt is driven in rotation by powerdelivered through the chain 194 to the sprocket 193 mounted on one endof the shaft 191 carrying the conveyor roller 189. As the endlessconveyor belt 188 moves in a counterclockwise fashion, as viewed inFIGURE 11, the excavated dirt is moved rearwardly in the framework 108and is deposited on the ground to the rear of the framework, or may beconveyed to a dump truck or otherwise handled as may be desired. Theroller positioned to the rear of the framework 108 and projectingslightly below the lower surface of the lower plate 126 functions toreduce the frictional drag which the framework 108 imposes on thetractor 106 and permits the apparatus to be moved forward more easily.

A modified embodiment of the invention is illustrated in FIGURES 17, 18and 19. The portion of this embodiment there illustrated comprises theframe carrying the conveyor mechanism and the cutter blades for slicingthrough the earth and removing the earth as the framework is advanced bya tractor or other suitable selfpowered vehicle (not shown). Theframework is designated generally by reference character 200 andincludes horizontally spaced, vertically extending side walls 202 and204. Mounted on the side wall 204 adjacent the forward vertical edge 206thereof, and at a position relatively high on the side wall is anoutside hitch bracket 208 having a plurality of horizontally spacedchannels and apertures 210 for facilitating the connection of an outsidehitch link thereto by use of a pin or other suitable means. A secondoutside hitch bracket 212 is provided in a corresponding position on theside wall 202 adjacent the front edge 214 thereof, and also includes aplurality of horizontally spaced channels defining horizontally alignedapertures 213 to accommodate a hitch pin. As in the case of theembodiment illustrated in FIGURES through 16, the hitch brackets 208 and212 provide points of connection for the outer or lateral hitch linksused in a three point hitch connection for connecting the framework 200to a tractor or other self-powered vehicle.

The vertically extending side walls 202 and 204 are interconnected by ahorizontally extending base plate 216 which extends between and issecured to the lower edges of the vertically extending side walls. Thehorizontal base plate 216 extends from the rear edges 218 of the sidewalls 202 and 204 to a position about two-thirds of the way forward onthe side walls where it terminates in a transversely extending forwardedge 220. A transmission housing, designated generally by referencecharacter 222, is welded or otherwise suitably secured to the uppersurface of the horizontal base plate 216 at a position relatively closeto the forward transverse edge 220 thereof, and extends horizontallyacross the framework 200 between the side walls 202 and 204. Thetransmission housing 222 includes a front wall 224, a back wall 226, anda horizontal cover plate 228. The construction of the transmissionhousing 222 is such that all of the intersecting walls and the coverplate are sealingly connected to each other so that the housing may befilled with a suitable lubricant, and the ingress of fine dust or waterto the interior of the housing is prevented.

Secured to the lower rear corners of the side walls 202 and 204 are apair of roller supporting brackets 230 which project rearwardly from theframework 200 and support suitable journal blocks 232 which receive theopposite ends of a shaft 234. The shaft 234 carries a roller 236 whichis keyed thereto and is positioned to roll along the surface of theground which is exposed after the cutter blades of the apparatus haveremoved the surface layer from the ground in the manner hereinafterdescribed.

A vertically extending partition and shaft housing assembly designatedgenerally by reference character 240 is positioned approximately midwaybetween the side walls 202 and 204, and extends upwardly to a positionslightly below the uppermost edges 242 of the vertically extending sidewalls 202 and 204. The vertical partition and shaft housing assembly 240comprises a rear portion which is constructed to include horizontallyspaced, vertically extending side plates 244, a top wall 246interconnecting the vertically extending side plates and a verticallyextending rear wall 248 interconnecting the side plates 244 (see FIGURES17 and 19). To the rear of the transmission housing 222, the verticallyextending side plates 244, and the vertically extending rear wall 248are of a length to extend to, and contact, the horizontal base plate216. A step is provided in the partition and shaft housing assembly topermit its forward end to fit over the transmission housing 222 so thatthe lower edges of the forward portions of the side plates 244 aresecured to the cover plate 228 of the transmission housing.

At its forward end, the partition and shaft housing assembly 240includes a pair of converging side plates 252 which are secured at theirrearmost vertical edges 254 to the forward edge of the side plates 244,and which converge to a common leading edge 256, as illustrated inFIGURE 17. The shaft housing assembly 240 thus has a V-shaped fonw-ardportion which permits the earth removed by the cutter blades, ashereinafter explained, to be cleanly and evenly divided by theconverging forward walls 252 of the shaft housing assembly and to flowpast the shaft housing with a minimum of frictional resistance.

The forward portion of the shaft housing assembly 240 is supported upona transverse blade support rod 250 which extends between, and isconnected at its ends to, the side walls 202 and 204 of the framework200. A .pair of inclined lift plates 262 are welded or otherwisesuitably secured at one of their end edges to the con verging forwardwalls 252 of the shaft housing assembly 240, and at their other endedges to the side walls 202 and 204 of the framework 200 (see FIGURES 17and 19). The lift plates 262 terminate with their leading edgesvertically spaced above the transverse blade sup port rod 260, as bestillustrated in FIGURE 18. The trailing edges of the inclined lift plates262 are secured to the forward edge of the cover plate 228 of the transmission housing 222.

For the purpose of receiving and moving toward the rear of the framework200, dirt moved onto the cover plate 228 of the transmission housing 222by the lift plate 262, a pair of endless belt conveyor assemblies,designated generally by reference characters 268 and 270, respectively,are positioned between the shaft housing assembly 240 and the two sidewalls 202 and 204. The conveyor assemblies 268 and 270 each include aforward roller 272 keyed to a shaft 274 which is journaled at itsopposite ends in the respective side plate 244 of the shaft housingassembly 240 and in the respective vertically extending side wall 202 or204. The conveyor assemblies 263 and 2 70 each further include a rearroller 276 keyed to a shaft 278 which is journaled at its opposite endsin appropriate journal housings 279 supported by the side walls 202 and204. The roller-s 276 and 272 of each conveyor assembly support anendless belt 280 which supports and moves the dirt from the cover plate228 of the transmission housing 222 to the rear of the frame 200. Theendless belts 230 of the conveyor assemblies 2&8 and 270 may be moved bydriving either of the rollers 272 and 27s in rotation by a suitableengine or motor carried on the framework 200 or, more desirably, by adriving belt or chain extended from the gearing located in a gear boxmounted on the frame 200 and subsequently described, through the shafthousing 240 to the shafts 278 which carry the rollers 276.

The power transmission system used in the em bod-iment of the inventionillustrated in FIGURES 17, 18 and 19 includes a power input shaft 284having a coupling member 286 disposed on the end thereof for couplingthrough a universal joint to the power takeoff of a tractor vehicle orother self propelled vehicle having a prime mover disposed thereon. Apower input shaft 284 passes through a journal box 28% mounted on theforward end of the shaft housing assembly 240 and through a cylindrical,lubricant packed casing 290 into a gear box 292 which is mounted on thetop of the shaft housing assembly 240 in the position best illustratedin FIG- URE 18. The journal box 288 has secured thereto a pair ofupwardly extending hitch plates 294 which are provided with alignedopenings or apertures 296 and which thus form a hitch bracketfacilitating the connection of the central hitch link (not shown) usedin a standard three point hitch connection to the framework 200.

Suitable gearing, such as a ring and pinion gear of the type illustratedin FIGURE 9, is disposed in the gear box 292 and is used to transmit therotational motion of the power input shaft 284 to a vertically extendingdrive shaft 300 illustrated in FIGURE 18. The ver- .tically extendingdrive shaft 300 passes downwardly in walls 202 and 204 thereof, andcarries a plurality of connect-ing pins 310 which are spaced atlongitudinal intervals along the drive plate. The pins 310 projectdownwardly from the drive plate 308 and are each secured at their lowerends to a cam plate 312. The cam plate 312 is supported by anti-frictionbearings in a cam plate support member 314 which extends transverselyacross the housing 200 and is positioned entirely within thetransmission housing 222. The cam plate support member 314 is secured inthe transmission housing 222 by welding or otherwise suitably attachingits opposite ends to the side walls 202 and 204 of the framework 200.

Each of the cam plates 312 has a downwardly projecting drive stud 316secured to the lower surface thereof in a position closely adjacent theperiphery of the cam plate, and the drive studs 316 are, in the case ofeach of the cam plates 312, disposed at different circumferentialspacings around the respective cam plates from the position ofattachment thereto of the connecting pins 310 secured to the lowersurface of the cam plate. The peripheral or circumferential spacing ofthe drive studs 316 and the pins 3 10 around the periphery of theseveral cam plates 312 is determined by the number of cutter blades,hereinafter described, which are to be utilized. The described spacingis incorporated in the apparatus for the purpose of driving the cutterblades in ou-t-of-phase relation to each other, and the sector of theperipheral surface of the several cam plates which is interposed betweenthe connecting pins 310 and the drive studs 316 is arrived at bydividing 360 degrees by the total number of cutter blades which areincorporated in the machine.

The drive studs 3 16 carried by the cam plates 312 are each engaged attheir lower ends by an upwardly projecting keywvay formed by a pair oftransversely extending, parallel guide rods 313 welded or otherwisesuitably secured across the top of a pair of tubular members 3120. Thetubular members 3 constitute portions of the cutter blade assembly whichwill next be described in detail.

The cutter blade assemblies are best illustrated in FIG- URES 18 and 19and are designated generally by reference character 32 2. A plurality ofthe assemblies are employed, and in the illustrated embodiment of theinrvention sixe of the assemblies are utilized. Each of the assemblies322 includes a cutter blade 323 having a sharpened cutting edge 323aformed at the forward or leading end thereof. The cutter blades 323 eachfurther include a shank portion 324 which has mounted thereon at therear edge of the cutter blades 32?: an angle iron bracket 326. The angleiron brackets 326 may be secured to the shank portions 324 of therespective cutter blades 32 3 by bolting, as illustrated in FIGURE 18,as well as by welding or other suitable means.

The forward ends of the tubular members 320 extend through the angleiron brackets 326 and are secured to the angle iron brackets so that thebrackets and the cutter blades 323 carrying the respective brackets aremade to move with the tubular members 320. It will be noted in referringto FIGURE 19 that a pair of the tubular members is extended through andconnected to the angle iron bracket 326 on each cutter blade 323, andthat each pair of tubular members 320 associated with each of thebrackets 326 is provided with the guide rods 318 in which one of thedrive studs 316 is caused to move, as hereinafter described. Each of thetubular members 320 extends through a sleeve 330 mounted on the outsideof the forward wall 224 of the transmission housing 222. Each of thesleeves 330 includes a packing gland (not shown) which forms afluid-tight seal around the respective tubular member 320 which passestherethrough so that the tubular member may reciprocate in the sleeve330 without loss of lubricating fluid contained within the transmissionhousing 222. There is also provided .a Sylphon or bellows structure 331which has one of its 16 ends secured around the sleeve 330 and its otherend around the forward portion of each tubular member 320.

At their ends opposite the ends which are passed through and secured tothe angle iron brackets 326, each of the tubular members 320telescopingly receives a cylindrical guide rod 334 which projectsinwardly from the rear wall 226 of the transmission housing 222 in themanner best illustrated in FIGURES 18 and 19. The guide rods 334 are ofa length to project a major portion of the transverse distance acrossthe transmission housing 222, and are firmly secured or anchored to therear wall 226 of the transmission housing 222 by welding, bolting, orany other suitablevmeans. The guide rods 334 fit slidingly within thetubular members 320 for purposes of guiding these members in theirreciprocating or rectilinear movement, as will be hereinafter describedin greater detail.

In the operation of the embodiment of the invention illustrated inFIGURES 17, 18 and 19, the framework 200 and the various structuralelements carried thereby are connected to a suitable self-poweredvehicle, such as a tractor of the type illustrated in FIGURES 1 and 10,using the three point hitch connection illustrated in FIG- URE 10 withthe outer hitch links being connected to the outer hitch brackets 208and 212 provided on the side walls 202 and 204 of the framework 200. Itshould be pointed out that the framework 200 can be elevated by the useof the hitch brackets in the same manner as has been previouslydescribed in referring to the embodiment shown in FIGURES 10 through 16,and that the framework may be pivoted about an axis extending throughthe hitch brackets 208 and 212 by manipulation of the central hitch linkwhich is attached to the central bracket formed by the vertical hitchplates 294. In this way, the excavating and pavement cutting apparatusof this embodiment may be regulated in the depth to which it penetratesthe soil.

The power for driving the blade assemblies 322 in rectilinear orreciprocating motion is developed from the self-powered vehicle, and istransmitted to the blade assemblies through the power input shaft 284which is connected through the coupling 286 to the power takeoff on thevehicle. The rotational motion of the power input shaft 284 istransmitted through suitable gearing in the gear box 292 to the driveshaft 300 which in turn drives the drive disc 304 in rotationalmovement. The rotational movement of the drive disc 304 is transmittedto the drive plate 308 which in turn drives each of the cam plates 312in rotational movement. The cam plates can move freely in the supportmember 314, and in undergoing rotational movement, impart rectilinearmotion to each pair of tubular members 320 connected to each of thecutter blades 323.

The timing of the stroke of each of the blades 323 is dependent upon thespacing of the respective drive stud 316 from the connecting pins 310around the periphery of the respective cam plate 312, as herein-beforedescribed. As each cam plate 312 rotates, its drive stud 316 bearsagainst the guide rods 318 and causes the tubular members 320 to moveforwardly and rearwardly with respect to the frame 200. Any transversecomponent of movement of the drive studs 316 with respect to the tubularmembers 320 results in movement of the drive studs transversely in thetrack provided by the guide rods 318, but does not effect any lateral ortransverse movement of the tubular members.

As the tubular members 320 are caused to reciprocate in the mannerdescribed, they are guided and supported by the cylindrical guide rods334 which are telescoped within the tubular members 320. The tubularmembers 320 slide easily through the sleeves 330 mounted on the forwardwall 224 of the transmission housing 222, and effectively push thecutter blades 323 forward from the framework into the earth during thecutting portion of the stroke, and then retract the blades toward theframe- 17 work following the cutting portion of the stroke. The severalblades 232 carry out their strokes in out-of-phase relation to eachother so that some of the blades are being retracted as other blades aremoving forward on the cutting portion of the stroke.

In addition to the general features and salient advantages which havehereinbefore been described as characterizing the earth excavating andpavement cutting devices of the present invention, the embodimentillustrated in FIGURES 17 through 19 possesses several additionaladvantageous structural features which should be briefly described. Insome operations in which it is desired to remove a crust or surfacelayer from the earth, and then redeposit this crust in substantially thesame location from which it was removed in a relatively undisturbedstate, it is desirable to provide a relatively low profile or slightinclination to the surfaces over which the dirt must move in passingfrom the front to the rear of the framework 200. The power transmissionused to drive the blade assemblies 322 of the FIGURES 17 through 19embodiment is particularly designed to permit this to be acomplished,being relatively compact and capable of confinement within a small spacenot requiring a large amount of room above the base plate 216.

Moreover, the manner in which the transmission is constructed and thespecific mounting arrangement utilized for the tubular members 320 usedto drive the blades 323 in their rectilinear motion lends itself toenclosure of the system within a fluid'tight transmission housing 222which can be filled with a lubricant which constantly bathes all of themoving parts except the drive shaft 300 and the power input shaft 284with the lubricant. The sealed system also has the advantage ofpreventing the ingress of any dirt or dust to the moving parts of thesystem. The manner in which the tubular members are supported and slidein the sleeves 330 and on the guide rods 334 permits the bladeassemblies 322 to be operated with a minimum of frictional drag orresistance, and it will be apparent in referring to FIGURES 18 and 19that the parts which are frictionally engaged during movement areconstantly subjected to immersion in the lubricating fluid.

The conveyor assemblies 368 and 370 which are positioned toward the rearof the framework 200 and are sloped gently upwardly fnom the cover plate278 of the transmission housing 222 also provide minimal resistance tothe flow of excavated dirt through the framework and to the rearthereof. It is also to be pointed out that the converging plates 252used in the forward portion of the shaft housing assembly 240 permit thedirt to be moved around and past the shaft housing assembly with aminimum of resistance or choking within the framework 200.

A further embodiment of the invention which is somewhat similar to thatshown in FIGURES 17, 18 and 19, but employing a different powertransmission system therein is illustrated in FIGURES 20 and 21. Thesimilarity of the embodiment shown in these figures to the embodimentwhich has been described immediately above and depicted in FIGURES 17,18 and 19 has prompted the use of identical reference numerals whereidentical parts are illustrated. It will thus be seen in referring toFIGURES 20 and 21 that the only difference in the construction of thisembodiment from that illustrated in the foregoing described figures isin the manner in which the gearing and transmission elements locatedwithin the transmission housing 222 are constructed and arranged.

In FIGURE 20, the drive shaft 300 extends through the journal 302mounted on the cover plate 228 of the transmission housing 222. Thelower end portion of the drive shaft 300 passes through a bearing 348 ina gear supporting plate 350 which extends transversely across thehousing 200, and is secured at its opposite ends to the side plates 202and 204. Secured to the lower end of the drive shaft 300 in a positionbelow the gear supporting plate 350 is a driving gear 352 which ispositioned substantially midway between the side walls 202 and 204. Thedriving gear 352 is keyed to the drive shaft 300 for rotation therewithand engages by teeth located on its outer periphery, a pair of largerdriven gears 354 disposed on opposite sides of the driving gear 352 andin transverse alignment beneath the transverse gear supporting plate350. The driven gears 354 are but two of a plurality of driven gearscorresponding in number to the number of cutter blades 323 which areemployed. The driven gears 354 are disposed in a transverse lineextending across the framework 200 and lying beneath the gear supportingplate 350. Each of the driven gears 354 meshes with the next adjacentdriven gear so that all of the driven gears 354 are driven from thedrive gear 352 located in the center of the framework 200 and keyed tothe drive shaft 300. Each of the driven gears 354 is supported on a stubshaft 355 which is journaled in a suitable bearing carried by the drivegear support plate 350. The driven gears 354 are also preferably movablysupported by suitable anti-friction bearings on a transverse lowersupport plate 360 which extends across the framework 200 and is securedat its opposite ends to the side walls 202 and 204.

Depending downwardly from the lower surface of each driven gear 354 is adrive stud 356' which is radially offset from the rotational axis of therespective driven gear 354. The drive studs 356 are circumferentiallyoffset from each other in their relation to the rotational axes of theseveral driven gears 354, and it is this circumferential spacing of theseveral drive studs 356 which permits the cutter blades 323 to bereciprocated in outof-phase relation to each other. As in the case ofthe drive studs 316 provided in the embodiment of the inventionillustrated in FIGURES 17, 18 and 19, the drive studs 356 attached tothe driven gears 354 and in the embodiment of the invention underdiscussion engage a trackway formed by a pair of transversely extendingguide rods 318 which are connected to the upper surfaces of the pair oftubular members 320 used to drive the blades 323.

The operation of the embodiment of the: invention illustrated in FIGURES20 and 21 is substantially identical to that described in referring tothe embodiment of FIGURES 17, 18 and 19. The advantage of the formerembodiment, however, is that the construction of the transmissionpermits even a lower profile dirt supporting and moving surface to beachieved, and thus permits less disturbance of the earth when it is tobe returned to its former position in certain types of agriculturalopera tions. The power transmission structure used in the embodiment ofthe invention illustrated in FIGURES 20 and 21 functions by taking therotational power input delivered by the drive shaft 300 and transmittingthis to rotational movement of the driven gears 354 as they are drivenby the driving gears 352. As the driven gears 354 rotate, theirrespective drive studs 356 engage the guide r-ods 318 and cause thevarious pairs of tubular members 320 included in the blade assemblies322 to undergo a reciprocating motion, causing the blades 323 to biteinto the earth in the manner hereinbefore described.

A different type of power transmission system used to drive the cutterblades in reciprocating movement is illustrated in FIGURES 22 and 23 ofthe drawings. This power transmission system is particularly useful inthe earth evacuating and pavement cutting apparatus of the invention inthat it permits a dirt supporting surface of very low profile to beobtained in the apparatus, and also facilitates synchronization betweenthe speed at which the self-powered vehicle towing the cutter bladecarrying framework is moved, with the rate at which the cutter bladesper se are reciprocated. An advantage of such synchronization is topermit the machine to be used with maximum effectiveness in varyingtypes of soils, or for removing surfacing materials of varying hardnessand consistencies. For example, in some instances it may be desirable tohave the self-powered vehicle moving in the direction of travel of theapparatus at substantially the same linear rate of speed as the bladesare moved forward in their cutting stroke, and retracted toward theframework following the cutting stroke. In this way, the relativemovement of the blades with respect to the earth during the retractionportion of the stroke is zero and no frictional drag is imposed upon themachine as a result of the necessity for the blades to move backwardlyor rearwardly through accumulated earth, and in scraping, frictionalengagement with the exposed surface of the earth from which the upperlayer has been removed.

Referring initially to FIGURE 22, a hydraulic fluid reservoir 380 isconnected by a conduit 381 to a hydraulic pump 382 which is powered by apower input shaft 384 adapted to be connected to the power takeoff onthe selfpowered vehicle or tractor (not shown). A suitable power outputshaft 386 is connected through suitable power transmission linkage (notshown) to the power input shaft 384 and is extended from the hydraulicpump 382 to a variable speed transmission housing 388.

The variable speed transmission housing 388 encloses adjustable gearing(not visible) which permits the rotational movement of the power outputshaft 386 to be transferred to a speed control shaft 390 through step-uor step-down transmission gearing which can be adjusted by use of agovernor screw 392 to permit the revolutions ratio between the poweroutput shaft 386 and the speed control shaft 390 to be varied as may bedesired for purposes hereinafter explained in greater detail. The speedcontrol shaft 390 extends through a fluid-tight bearing 394 provided inone of the end walls 396 of a manifold housing 398. The opposite end ofthe speed control shaft 390 is journaled in the opposite end wall 396 ofthe manifold housing 398 to permit the speed control shaft to be rotatedin the manifold housing.

The speed control shaft 390 carries a solid drum 400 which is keyed tothe speed control shaft for rotation therewith. The drum 400 is formedwith a plurality of fluid injection and fluid discharge ports extendingdiametrically through the drum, with the fluid injection ports beingdesignated by reference characters 402, 404, 406 and 408. The fluiddischarge ports are designated by reference characters 410, 412, 414 and416. It will be noted that the fluid injection and discharge ports 402through 416 which are provided in the drum 400 extend through the drumat different angles and have variously positioned openings on theperiphery of the drum as shown in FIG- URES 22 and 24. Each adjacentpair of fluid injection and discharge ports, such as, for example, theports 402 and 410, have openings on the periphery of the drum 400 whichextends through arcs of 90 and are offset from each other in acircumferential direction by 90 (see FIGURES 24a-24f). The purpose ofthis arrangement will be subsequently explained.

The manifold housing 398 encloses a cylindrical drum housing 420 whichsealingly surrounds the drum 400. The manifold housing 398 also includesa partition 422 which divides the portion of the manifold housing 398outside the drum housing 420 into a discharge manifold space 424 and aninjection manifold space 426. The injection manifold space 426 is placedin communication with the interior of the drum housing 420 by aplurality of tubular injection passageways 430, 432, 434 and 436 whichcorrespond in number to the number of cutter blades used in theapparatus. A conduit 438 interconnects the injection manifold space 426with the hydraulic pump 382 and a conduit 440 interconnects thedischarge manifold space 424 with the reservoir 380.

The drum housing 420 is provided with a plurality of fluid dischargepassageways 446, 448, 450, and 452 which place the interior of the drumin communication with the discharge manifold space 424. The fluidinjection passageways 430-436 are positioned in coplanar alignment withthe fluid discharge passageways 446-452, and the several passageways arelongitudinally aligned with the transverse planes through the drum 400which contain the respective fluid injection ports 402-408 and fluiddischarge ports 410-416.

Disposed on the opposite side of the drum housing 420 from the injectionand discharge passageways 430-452, and in coplanar alignment therewith,are a plurality of fluid injection and discharge conduits 402a-416a,each of which communicates with the interior of the drum housing 420.The fluid injection and discharge conduits are numbered according to therespective fluid and discharge ports with which they register duringrotation of the drum 400. Thus, the fluid injection conduit 402aregisters with the fluid injection port 402, the fluid discharge conduit410a registers with the fluid discharge port 410, the fluid injectionconduit 404a registers with the fluid injection port 404, etc. Theperiod of registry or communication is in each case equal to one-fourththe period of one revolution of the drum 400, and the communication isestablished between each port and its respective injection or dischargeconduit twice during each revolution of the drum. The circumferentialspacing of degrees between the peripheral openings of the dischargeports 410-416 from the peripheral openings of the injection ports402-408 (between each adjacent pair thereof) assures that uponcompletion of the period of communication between an injection port andits aligned injection conduit, the period of communication between theadjacent discharge port and its aligned discharge conduit will becommenced.

The fluid injection conduits 402a-408a, and fluid discharge conduits410a-416a are connected at their ends opposite the ends entering thedrum housing 420 to a piston housing designated generally by referencecharacter 460. The piston housing 460 is partitioned or divided into aplurality of piston chambers 462, 464, 466, and 468 by a plurality oftransversely extending partitions 470, 472, and 474 with the number ofpiston chambers provided being equal to the number of cutter bladeswhich are to be used in the apparatus. Mounted within each of the pistonchambers 462-468 for reciprocating movement therein is a piston 476.Each of the pistons 476 is generally rectangular in configuration andcarries studs or protuberances 476a at each of its ends which slidinglyengage guide slots 479 formed in the respective partitions 470- 474 withwhich the ends of the respective piston are in contact. This arrangementof the mounting of the pistons 476 is best illustrated in FIGURE 23. Theperipheral surfaces of the pistons 476 are provided with a rubber gasket481 or other suitable sealing member to prevent by-pass of fluid by thepiston during operation of the apparatus.

The transverse partitions 470 and 474 are each provided with an air ventport 477 disposed in the forward portion thereof so as to permit the airlocated in the piston chambers 462-468 on the forward side of thepistons 476 to be vented into the next adjacent piston chamber duringthe cutting stroke of the pistons, as hereinafter described. Connectedto each of the pistons 476 and extending through the forward wall 478 ofthe piston housing 460 are a pair of piston rods 480 which are securedto an angle iron or flange 482 bolted, welded, or otherwise suitablysecured, to the shank portion 484 of a cutter blade designated generallyby reference character 486. Thus, each of the cutter blades 486 isdriven through two piston rods 480 by one of the pistons 476 containedin each of the piston chambers 462-468.

The operation of the power transmission system depicted in FIGURES 22-24commences when the hydraulic pump 382 is energized by power deliveredthereto from the power takeoff of the tractor via the power input shaft384. Simultaneously with the actuation of the hydraulic pump 382, thepower output shaft 386 is caused 2.1 to rotate. It should be pointed outthat the power output shaft 386 may be merely an extension of the powerinput shaft 384, or the two shafts may be connected by a suitablekinematic chain which does not interfere with the operation of thehydraulic pump 3 82.

As the hydraulic pump 382 is actuated, hydraulic fluid is drawn from thereservoir 380 via the conduit 381 and is circulated through the conduit438 from the hydraulic pump to the injection chamber 426 of the manifoldhousing 3-98. Hydraulic power fluid contained within the injectionmanifold space 426 is passed through one of the injection passageways430-436 at a time when the corre sponding injection port 402-408 in thedrum 400 is aligned therewith.

It has been previously pointed out that the injection ports 402-408 inthe drum 400 are each provided with opposed peripheral openings on thedrum which each extend over 90 degrees of the circumference of the drum.The injection ports thus each become aligned and in communication withtheir respective injection passageways 430-436 twice during eachrotation of the drum, with each period of communication being equal toone-fourth the total period of one drum revolution. The circumferentialarrangement of the injection ports 402-408 and discharge ports 410-416is such that, for example, when the injection port 402 becomes alignedwith its respective injection passageway 430, the discharge port 410-which is paired with the injection port 402 is out of alignment withboth its respective discharge passageway 446 and its respectivedischarge conduit 410a. It will thus b seen that hydraulic power fluidis injected into the piston chamber 462 via the injection passageway430, injection port 402, and injection conduit 402a at this time, but nohydraulic power fluid is permitted to leave the chamber 462 by reason ofthe non-alignment of the discharge port 410 with the discharge conduit410a and the discharge passageway 446.

The piston 476 in the piston chamber 462 is thus driven forward to causethe blade 486 carried by its piston rods 480 to be driven into the earthahead of the excavating apparatus. Air ahead of the piston is ventedthrough the air vent port 476 into the adjacent piston chamber 464, andthus forces the piston 476 carried therein rearwardly or into aretraction stroke. It is thus necessary that the discharge port 412 bealigned with its respective discharge conduit 41 2a and dischargepassageway 448 during a major portion of the cutting stroke of thepiston 476 located in the piston chamber 462. Stated diiferently, thedischarge port 412 is passed through the drum 400 at substantially thesame angle, and opens at both ends over the same sector of the peripheryof the drum, as the injection port 402 so that hydraulic power fluidcontained within the piston chamber 464 may be discharged therefrom atthe time that hydraulic power fluid is being introduced to the pistonchamber 462.

Upon completion of the cutting stroke of the piston 476 located in thepiston chamber 462, the injection port 402 will move out of registry orcommunication with its respective injection conduit 402a and injectionpassageway 430 so that the flow of hydraulic power fluid to the pistonchamber 462 is interrupted. Just as the injection port 402 moves out ofregistry with the injection conduit 402a after 90 degrees of rotation ofthe drum 400, the discharge port 410 is moving into registry with thedischarge conduit 410a and the discharge passageway 446. The piston 476in the piston chamber 462 is thus ready to be retracted, and todischarge hydraulic fluid from the piston chamber 462 through thedischarge conduit 410a, the discharge port 410, and the dischargepassageway 446 into the manifold discharge space 424.

At the same time that the discharge port 410 moves into communicationwith the discharge conduit 410a and the discharge passageway 446, theinjection port 404 is moving into communication with the injectionconduit 404a and the injection passageway 43 2. Hydraulic power fluidcan thus at this time be admitted to the piston chamher 464 from themanifold injection space 426 and can drive the piston 476 containedtherein forward in a cutting stroke. The flow of air through the airvent port 476 is reversed and, combined with the resistance offered bythe dirt ahead of the excavating apparatus to the movement of the blade484 carried by the piston 476 located in chamber 462, causes this pistonto move rearwardly and force hydraulic power fluid out of the chamber462 and into the manifold discharge space 424 via the discharge conduit410a, the discharge port 410 and the discharge passageway 446.

The manner in which the remaining two pistons located in the pistonchambers 466 and 468 are synchronized in their movements issubstantially identical to that which has been described with respect tothe pistons located in piston chamber-s 462 and 464. It should bepointed out, however, that the injection port 406 is set on a differentangle, and its openings in the cylinder 400 include differentcircumferential angles on the drum, than either of the injection ports402 or 404, and the same is true of the injection port 408. Thedischarge ports 414 and 416 also extend at an angle with respect to thedischarge ports 410 and 412. The effect of this angular arrangement isto cause the blades 486 carried by the pistons disposed in the pistonchambers 466 and 468 to undergo the cutting and retraction phases oftheir strokes at different times from the cutting and retraction strokesof the blades carried by the pistons 476 located in the chambers 462 and464. Thus, the out-o f-phase cutting action of the cutter blades whichhas been hereinbefore described in referring to other embodiments ofthis invention is attained in the hydraulic drive system depicted inFIG- URES 22, 23 and 24.

As fluid is sequentially discharged through the respective dischargeconduits 4l0a-416a, discharge ports 410-416 and discharge passageways446-452, the hydraulic power fluid accumulating in the manifolddischarge space 324 returns to the power fluid reservoir 380 by way ofthe discharge conduit 440. The cycle of the hydraulic power fluid isthus completed.

An important aspect of the type of drive system illustrated in FIGURES22 and 23 as incorporated in the earth excavating and pavement removingapparatus of the present invention is the ability to synchronize thelinear speed of the cutter blades 486 during their reciprocation withthe forward movement of the self-powered vehicle which moves theframework carrying the transmission apparatus and blade assemblies alongthe ground during operation of the device. With a given speed ofrotation of the power input shaft 384 as developed from the powertakeoff on the tractor, the tractor will move at a corresponding linearspeed or rate of advance over the surface of the ground. The poweroutput shaft 386 will also be correlated to the speed of the tractor,and will increase or decrease in rotational speed as the speed of thetractor is increased.

The rate at which the cutter blades 486 are reciprocated by thehydraulic power fluid will, however, be determined by the rotationalspeed of the power output shaft 306, and by the speed at which thisshaft is permitted to drive the speed control shaft 390. By a properadjustment of the governor screw 392, the gear ratio between the shafts386 and 390 may be varied to vary the speed of the speed control shaft390 and thus vary the speed of rotation of the drum 400. By varying thespeed of rotation of the drum 400, the period of time over which theseveral injection ports 402-408 and discharge ports 410-416 aresequentially in communication with their corresponding injectionconduits 402a-40i8a and discharge conduits 410a-416a, and also thecorresponding injection and discharge passageways, can be varied asdesired. Thus, the length of the strokes of the blades 486 can becontrolled and, provided the hydraulic pump 382 develops suificientpower, the speed of the stroke of each of the blades 486 can also becontrolled. This

35.EXCAVATING APPARATUS FOR REMOVING A SURFACE LAYER FROM THE EARTHCOMPRISING: A PRIME MOVER; A POWER TAKEOFF FROM SAID PRIME MOVER; AFRAMEWORK HAVING A TOP PORTION, A FORWARD PORTION, A REAR PORTION AND AGROUND ENGAGING PORTION; A PAIR OF OUTER HITCH BRACKETS MOUNTED ON THEFORWARD PORTION OF SAID FRAMEWORK ADJACENT THE SIDES OF SAID FRAMEWOFKAND IN HORIZONTAL ALIGNMENT WITH EACH OTHER; A CENTRAL HITCH BRACKETMOUNTED ON SAID FRAMEWORK TOWARD THE CENTER THEREOF AND VERTICALLYOFFSET FROM THE LINE OF HORIZONTAL ALIGNMENT OF SAID OUTER HITCHBRACKETS WHEREBY SAID FRAMEWORK CAN BE PIVOTED ABOUT A HORIZONTAL AXISEXTENDING THROUGH SAID OUTER HITCH BRACKETS BY A HITCH LINK CONNECTED TOSAID CENTRAL HITCH BRACKETS; ACTUATING MEANS CONNECTED TO SAID HITCHBRACKETS FOR ACTUATING SAID HITCH BRACKETS TO MOVE SAID FRAMEWORKRELATIVE TO A PLANE SUBSTANTIALLY COPLANAR WITH THE SURFACE OF THEGROUND OVER WHICH SAID EXCAVATING APPARATUS IS MOVED; A PLURALITY OFCUTTER BLADES MOVABLY MOUNTED ON THE FORWARD PORTION OF SAID FRAMEWORKIN ALIGNMENT WITH THE GROUND ENGAGING PORTION THEREOF; DIRT SUPPORTINGMEANS EXTENDING UPWARDLY AND REARWARDLY IN SAID FRAMEWOFK FROM A LINE INJUXTAPOSITION TO THE UPPER SURFACE OF SAID CUTTER BLADES TO RECEIVEMATERIAL SEVERED BY SAID CUTTER BLADES AND SUPPORT AND LIFT SAIDMATERIAL AS IT MOVES REARWARDLY WITH RESPECT TO SAID FRAMEWORK; ANDPOWER TRANSMISSION MEANS ON SAID FRAMEWORK AND HAVING AN INPUT ENDCONNECTED TO SAID POWER TAKEOFF AND AN OUTPUT END CONNECTED TO SAIDCUTTER BLADES FOR RECIPROCATING AT LEAST TWO OF SAID CUTTER BLADES ONSAID FRAMEWORK IN OUT-OF-PHASE RELATION TO EACH OTHER AND IN A DIRECTIONOF MOVEMENT ADVANCING FROM, AND RETURNING TO, THE FORWARD PORTION OFSAID FRAMEWORK, SAID POWER TRANSMISSION MEANS INCLUDING TIMING MEANSADAPTED TO MOVE AT LEAST ONE OF SAID BLADES FORWARDLY WITH RESPECT TOSAID FRAMEWORK AT A DIFFERENT TIME THAN THE TIME AT WHICH ANOTHER OFSAID BLADES IS MOVED FORWARDLY WITH RESPECT TO SAID FRAMEWORK, SAIDTIMING MEANS BEING DISPOSED BENEATH SAID DIRT SUPPORTING MEANS AND TOTHE REAR OF SAID CUTTER BLADES.